Quantitative and Automatic Echographic Monitoring of Labor Progression

Nowadays the decision between Caesarean Sections (CS), natural or operative child delivery is taken upon interpretation of manually measured anatomical parameters and recorded fetal heart rate, exposing the clinical staff and patients to human errors and determining the continuously rising rate of CS above the ideal 15% recommended by the World Health Organization. This study introduces a new method for non-invasive, quantitative and automatic monitoring of childbirth labor progression. We combined an ultrasound system with a real-time tracking algorithm in order to automatically measure labor progression parameters, like head station, head position, progression angle, based on patient specific anatomical references [Patent no. PCT/EP2009/008321]. A 2D digital echograph connected to a PC for real-time image processing was employed to measure fetal head station (FHS) and progression angle (PA). A quantitative validation study was carried out on a birth simulator, consisting of fetal and maternal mannequins immersed in water. Then, a preliminary intrapartum B-mode imaging study was conducted on patients by means of the developed methods and corresponding algorithms. In the birth simulator, the automatic identification was correct in 98% of the computed images providing high visual reliability for the operator. The average errors (expressed as bias +/- SD) were 0.8 +/- 1.9 mm for FHS and 3 degrees +/- 4 degrees for the PA. Accuracies improve of about 30% by reducing the frame-rate to be processed, i.e. from 1 fps to 0.2 fps, which is still suitable for the purpose. The methodology has been successfully validated in preliminary intrapartum echographic monitoring.